1. STR: A Simple and Efficient Algorithm for R-Tree Packing

2. Overview R Tree Packing Nearest –X Hilbert Sort Sort –Tile Recursive Results

3. Packing Disadvantages of inserting one element at a time into a R-Tree : –High load time –Suboptimal space utilization –Poor R-Tree structure Preprocessing advantageous for static data Nearly 100% space utilization and improved query times

4. R-Tree Packing Algorithms Nearest X Hilbert Sort Sort-Tile-Recursive

5. Basic Algorithm Preprocess the data file so that the T rectangles are ordered in [r/b] consecutive groups of b rectangles, where each group of b is intended to be placed in the same leaf level node. Load the [r/bl groups of rectangles into pages and output the (MBR, page-number) for each leaf level page into a temporary file. Recursively pack these MBRs into nodes at the next level, proceeding upwards, until the root node is created.

6. Nearest-X Rectangles are sorted by x-coordinate (center of the rectangle) Rectangles are then ordered into groups of size b.

7. Hilbert Sort

8. Sort-Tile-Recursive Sort the rectangles by x-coordinate and partition them into S vertical slices. A slice consists of a run of S*b rectangles. Sort the rectangles of each slice by y- coordinate. Pack them into nodes by grouping them in size of b. P = [r/b] S = √P

9. Classes of Data Uniformly distributed point and region data Mildly skewed line segment data (TIGER) Highly Skewed in location and size region data (VLSI) Highly skewed, in terms of location, point data (CFD).

10. Uniformly Distributed Data Hilbert sort 42% more disk accesses than STR for both point and range query. NX algorithm performs well as well as STR for point queries

11. Mildly skewed Data HS algorithm requires up to 49% more disk accesses than STR for both point and region queries. As region size increases, the difference between STR and HS becomes smaller.

12. Highly Skewed Data For region data, HS performed 3% - 11% faster than STR for point queries and roughly the same for region queries. For point data, HS required 11- 68% more disk access than STR for point queries, and roughly the same for region queries.

13. Conclusions All algorithms based on heuristics None of them is best for all datasets NX is not competitive Decision of using HS or STR is dependent on the type of the dataset Importance of choosing a packing algorithm is diminished as either the query size or the buffer size increase